Workpiece holding clamp mechanism of a forging machine

ABSTRACT

A workpiece holding clamp mechanism includes first and second clamp arms associated with respective clamp jaws. The first clamp arm is mounted on a transmission shaft, and has a sleeve part sleeved onto the transmission shaft, a first prong extending axially from the sleeve part and having a shaft receiving recess, a second prong extending axially from the sleeve part and spaced apart transversely from the transmission shaft, and a connection part bridging the first and second prongs. The first and second prongs cooperate with the sleeve part and the connection part to confine a receiving space which is aligned with a key groove of the transmission shaft into which a key is inserted. The connection part reduces an incidence of crack formation due to stresses in the first clamp arm.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a forging machine, more particularly to an improvement relating to a workpiece holding clamp mechanism of a forging machine.

2. Description of the Related Art

Generally, forgings, such as screws and nuts are manufactured by feeding a rod-like material from a roll of raw material into a forging machine, where the material is straightened and cut into workpieces with a predetermined length. The workpieces are clamped and transported to a plurality of punching units to undergo a series of punching and forging processes, and the resulting semi-products are transported to next stations for subsequent operations, such as tapping, thread forming, etc.

Referring to FIGS. 1, 2 and 3, a forging machine 1 typically includes a machine body 11, a clamp holder seat 12 mounted on the machine body 11, a plurality of roller frames 13 connected pivotally to the clamp holder seat 12, a plurality of cam wheels 14 mounted on the machine body 11 to push the respective roller frames 13, a slide plate 15 capable of reciprocating movement relative to the clamp holder seat 12, and a plurality of workpiece holding clamp mechanisms 2. For the sake of simplicity, only one roller frame 13 and one cam wheel 14 are shown in FIG. 1.

The number of the roller frames 13 corresponds to that of the workpiece holding clamp mechanisms 2. The workpiece holding clamp mechanisms 2 are mounted on the slide plate 15 and each include a transmission shaft 21 extending through the slide plate 15 and projecting leftwards and rightwards, a swing arm 22 mounted on the left end of the transmission shaft 21, a first clamp arm 23 mounted on the right end of the transmission shaft 21, a driven shaft 24 parallel to the transmission shaft 21 and extending through the slide plate 15, two meshing sector gears 25 mounted respectively on the transmission and driven shafts 21, 24, a second clamp arm 26 mounted on the driven shaft 24 proximate to the first clamp arm 23, first and second clamp jaws 27, 27′ connected respectively to the first and second clamp arms 23, 26, and a returning spring 28 mounted on the slide plate 15 to bias the first clamp arm 23.

When the cam wheel 14 drives the roller frame 13 to swing, the roller frame 13 pushes the swing arm 22 so that the transmission shaft 21 rotates itself and further drives the driven shaft 24 to rotate in an opposite direction. The first and second clamp arms 23, 26 are therefore actuated to swing in opposite directions so that the first and second clamp jaws 27, 27′ are opened and moved away from each other, thereby compressing the returning spring 28. When the cam wheel 14 stops camming the roller frame 13, the returning spring 28 returns to its original position and biases the first clamp arm 23 and the related components to swing so that the first and second clamp jaws 27, 27′ are closed.

Referring to FIGS. 4 and 5, the transmission shaft 21 has two key grooves 211, 212. The swing arm 22 includes a sleeve part 221 sleeved around the transmission shaft 21 proximate to the key groove 211 and having a through hole 222, a first prong 223 extending axially from the sleeve part 221 and having a recess of substantially semi-circular cross-section that extends axially from the through hole 222 to receive one side of the drive shaft 21 opposite to the key groove 211, a second prong 223′ extending axially from the sleeve part 221 and spaced apart transversely from the transmission shaft 21, and a pair of lugs 224 projecting radially from the sleeve part 221. A key 225 is placed between the first and second prongs 223, 223′ and is inserted into the key groove 211. The key 225 is locked in the key groove 211 by means of two locking screws 226 which penetrate through two respective screw holes formed in the second prong 223′ and which have ends pushing the key 225 against the key groove 211. A roller 227 is mounted between the lugs 224 to be actuated by the roller frame 13.

Like the swing arm 22, the first clamp arm 23 also includes a sleeve part 231, first and second prongs 233, 233′, a key 235, and locking screws 236. The connection between the first clamp arm 23 and the transmission shaft 21 is similar to that of the swing arm 22 and the transmission shaft 21. However, the first clamp arm 23 has a passive extension part 237 to be biased by the returning spring 28, instead of having the lugs 224 of the swing arm 22. In addition, a lower extension part 238 projects from the sleeve part 231 to connect with the first clamp jaw 27.

Since the swing arm 22 and the first clamp arm 23 are mounted on the transmission shaft 21 while interacting with the roller frame 13 and the returning spring 28, respectively, the swing arm 22 and the first clamp arm 23 are subjected to torsion forces during the forging operation. Generally, stresses due to such torsion forces are concentrated at the juncture of each sleeve part 222, 232 and the corresponding prong 223, 223′ , 233, 233′ so that cracks can easily occur in the swing arm 22 and the first clamp arm 23. Such cracks might affect adversely the accuracy of the operation of the swing arm 22 and the first clamp arm 23. Thus, the life of the swing arm 22 and the first clamp arm 23 is usually short, and frequent replacement thereof is necessary, thereby reducing the production efficiency and increasing the manufacturing costs.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a workpiece holding clamp mechanism with a robust construction so as to prolong the life of the workpiece holding clamp mechanism.

According to one aspect of the present invention, a workpiece holding clamp mechanism comprises: first and second clamp arms which have first and second clamp jaws, respectively, and which are turnable to open or close the first and second clamp jaws; and a transmission shaft having a key groove. The first clamp arm is mounted on the transmission shaft, and includes a sleeve part sleeved onto the transmission shaft proximate to the key groove and having a shaft receiving hole, a first prong extending axially from the sleeve part and having a shaft receiving recess which extends axially from the shaft receiving hole, a second prong extending axially from the sleeve part and spaced apart transversely from the transmission shaft, and a connection part bridging the first and second prongs. The first and second prongs cooperate with the sleeve part and the connection part to confine a receiving space which is aligned with the key groove. The first clamp arm further includes a key disposed within the receiving space and inserted into the key groove, and a fastener that extends through the second prong and locks the key in the key groove.

According to another aspect of the present invention, a workpiece holding clamp mechanism comprises: a transmission shaft having a first key groove; a driven shaft parallel to and driven by the transmission shaft; a swing arm mounted on the transmission shaft; a first clamp arm mounted on the transmission shaft opposite to the swing arm; and a second clamp arm mounted on the driven shaft.

The swing arm includes a sleeve part sleeved onto the transmission shaft proximate to the first key groove and having a shaft receiving hole, a first prong extending axially from the sleeve part and having a shaft receiving recess which extends axially from the shaft receiving hole, a second prong extending axially from the sleeve part and spaced apart transversely from the transmission shaft, and a connection part bridging the first and second prongs. The first and second prongs cooperate with the sleeve part and the connection part to confine a receiving space which is aligned with the first key groove. The swing arm further has a key disposed within the receiving space and inserted into the first key groove, and a fastener that extends through the second prong and locks the key in the first key groove.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment with reference to the accompanying drawings, of which:

FIG. 1 is a fragmentary front view of a conventional workpiece holding clamp mechanism of a forging machine;

FIG. 2 is a plan view showing the workpiece holding clamp mechanism of FIG. 1;

FIG. 3 is a side view showing the workpiece holding clamp mechanism of FIG. 1;

FIG. 4 is an exploded view of the workpiece holding clamp mechanism of FIG. 1;

FIG. 5 is a sectional view of the workpiece holding clamp mechanism of FIG. 1;

FIG. 6 is an exploded view showing a workpiece holding clamp mechanism embodying the present invention;

FIG. 7 is a sectional view of the workpiece holding clamp mechanism of FIG. 6;

FIG. 8 is a fragmentary sectional view taken along line 8-8 of FIG. 6; and

FIG. 9 is a fragmentary sectional view taken along line 9-9 of FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 6, 7, 8 and 9, a workpiece holding clamp mechanism 3 embodying the present invention is shown to be mounted on the slide plate 15 of the conventional forging machine. Like the prior art, the workpiece holding clamp mechanism 3 includes a swing arm 5 and a first clamp arm 6 both of which are mounted on a transmission shaft 4, and a second clamp arm 7 mounted on a driven shaft 8 which is driven by the transmission shaft 4.

The transmission shaft 4 extends through the slide plate 15 and includes two end portions on two opposite sides of the slide plate 15, and first and second key grooves 42, 42′ respectively formed in the end portions.

The swing arm 5 is mounted on one of the end portions of the transmission shaft 4 and is actuated by a roller frame (shown at 13 in FIG. 1) to swing itself and to rotate the transmission shaft 4 to and fro. The swing arm 5 includes a sleeve part 51 disposed around the transmission shaft 4 and having a shaft receiving hole 511 that receives the transmission shaft 4, a first prong 512 extending axially from the sleeve part 5 and having a shaft receiving recess 5121 of substantially semi-circular cross-section extending axially from the shaft receiving hole 511 to receive one side of the transmission shaft 4, a second prong 512′ extending axially from the sleeve part 51 and spaced apart from the transmission shaft 4, and a key 52.

The present invention resides in a connection part 513 that bridges the first and second prongs 512, 512′ and that is spaced apart from the sleeve part 51. Preferably, the connection part 513 is formed as one piece with the sleeve part 51 and the first and second prongs 512, 512′. The key 52 is disposed within a receiving space 514 which is defined by the sleeve part 51, the first and second prongs 512, 512′, and the connection part 513 and which is aligned with the first key groove 42. The key 52 is further inserted into the first key groove 42 and is locked therein by two fasteners, i.e. locking screws 53 which extend threadedly through the second prong 512′ and which have ends abutting against the key 52.

The sleeve part 51 further has two spaced apart lugs 515 which project radially from the sleeve part 51, and a roller 54 mounted rotatably between the lugs 515. The roller 54 is provided to abut against the roller frame 13 (see FIG. 1).

The first clamp arm 6 is mounted on the other end portion of the transmission shaft 4 and has a construction substantially similar to that of the swing arm 5. In particular, the first clamp arm 6 includes a sleeve part 61 disposed around the transmission shaft 4 and having a shaft receiving hole (not shown) for receiving the transmission shaft 4, a first prong 612 extending axially from the sleeve part 61 and having a shaft receiving recess 6121 of substantially semi-circular cross-section extending axially from the shaft receiving hole to receive one side of the transmission shaft 4, a second prong 612′ extending axially from the sleeve part 51 and spaced apart from the transmission shaft 4, and a key 62.

The present invention further resides in a connection part 613 that bridges the first and second prongs 612, 612′ and that is spaced apart from the sleeve part 61. Preferably, the connection part 613 is formed as one piece with the sleeve part 61, and the first and second prongs 612, 612′. The key 62 is disposed within a receiving space 614 which is defined by the sleeve part 61, the first and second prongs 612, 612′, and the connection part 613 and which is aligned with the second key groove 42′. The key 6 is further inserted into the second key groove 42′ and is locked therein by two fasteners, i.e. locking screws 63 which extend threadedly through the second prong 612′ and which have ends abutting against the key 62. As a result, the first clamp arm 6 is fastened firmly to the transmission shaft 4.

The first clamp arm 6 does not have any components corresponding to the lugs 515 and the roller 54 of the swing arm 5. Rather, the first clamp arm 6 is provided with a lower extension 615 which extends downward from the sleeve part 61 to connect with the first clamp jaw (see numeral 27 in FIG. 3), and an upper extension 616 which extends upward from the sleeve part 61 to connect with the returning spring (see numeral 28 in FIG. 3).

The second clamp arm 7 is rotated by the driven shaft 8 which rotates in a direction opposite to that of the transmission shaft 4 like the second clamp arm 26 of the prior art described hereinbefore.

When the swing arm 5 is actuated to rotate the transmission shaft 4, the first and second clamp arms 6 and 7 are turned in opposite direction so that the first and second clamp jaws attached thereto are closed. When the swing arm 5 is not actuated, the upper extension 616 is moved by the returning spring (see FIG. 3) so that the first clamp arm 6 is returned and moves the transmission shaft 4 and the second clamp arm 7. The first and second clamp jaws attached to the first and second clamp arms 6 and 7 can therefore be opened. Although the swing arm 5 and the first clamp arm 6 will encounter torsional forces during their operations, because of the use of the connection parts 513, 613 which reinforce the swing arm 5 and the first clamp arm 6, the incidence of crack formation due to stress concentration can be reduced and the life of the swing arm 5 and the first clamp arm 6 can be prolonged.

While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements. 

1. A workpiece holding clamp mechanism comprising: first and second clamp arms which have first and second clamp jaws, respectively, and which are turnable to open or close said first and second clamp jaws; a transmission shaft having a key groove; and said first clamp arm being mounted on said transmission shaft, and including a sleeve part sleeved onto said transmission shaft proximate to said key groove and having a shaft receiving hole, a first prong extending axially from said sleeve part and having a shaft receiving recess which extends axially from said shaft receiving hole, a second prong extending axially from said sleeve part and spaced apart transversely from said transmission shaft, and a connection part bridging said first and second prongs, said first and second prongs cooperating with said sleeve part and said connection part to confine a receiving space which is aligned with said key groove; said first clamp arm further having a key disposed within said receiving space and inserted into said key groove, and a fastener that extends through said second prong and that locks said key in said key groove.
 2. The workpiece holding clamp mechanism as claimed in claim 1, wherein said connection part is formed as one piece with said first and second prongs and said sleeve part.
 3. The workpiece holding clamp mechanism as claimed in claim 1, wherein said first clamp arm further has a lower extension that projects downward from said sleeve part and that is connected to said first clamp jaw.
 4. The workpiece holding clamp mechanism as claimed in claim 3, further comprising a returning spring, said first clamp arm further including an upper extension that projects upward from said sleeve part to be biased by said returning spring.
 5. A workpiece holding clamp mechanism comprising: a transmission shaft having a first key groove; a driven shaft parallel to and driven by said transmission shaft; a swing arm mounted on said transmission shaft, said swing arm including a sleeve part sleeved onto said transmission shaft proximate to said first key groove and having a shaft receiving hole, a first prong extending axially from said sleeve part and having a shaft receiving recess which extends axially from said shaft receiving hole, a second prong extending axially from said sleeve part and spaced apart transversely from said transmission shaft, and a connection part bridging said first and second prongs, said first and second prongs cooperating with said sleeve part and said connection part to confine a receiving space which is aligned with said first key groove, said swing arm further having a key disposed within said receiving space and inserted into said first key groove, and a fastener that extends through said second prong and that locks said key in said first key groove; a first clamp arm mounted on said transmission shaft opposite to said swing arm; and a second clamp arm mounted on said driven shaft.
 6. The workpiece holding clamp mechanism as claimed in claim 5, wherein said connection part is formed as one piece with said sleeve part and said first and second prongs.
 7. The workpiece holding clamp mechanism as claimed in claim 5, wherein said swing arm further includes a pair of spaced apart lugs projecting radially from said sleeve part, and a roller mounted between said lugs.
 8. The workpiece holding clamp mechanism as claimed in claim 5, wherein said transmission shaft further includes a second key groove, said first clamp arm including a sleeve part sleeved onto said transmission shaft proximate to said second key groove and having a shaft receiving hole, a first prong extending axially from said sleeve part of said first clamp arm and having a shaft receiving recess which extends axially from said shaft receiving hole of said first clamp arm, a second prong extending axially from said sleeve part of said first clamp arm and spaced apart transversely from said transmission shaft, and a connection part bridging said first and second prongs of said first clamp arm, said first and second prongs of said first clamp arm cooperating with said sleeve part and said connection part of said first clamp arm to confine a receiving space which is aligned with said second key groove, said first clamp arm further having a key disposed within said receiving space of said first clamp arm and inserted into said second key groove, and a fastener that extends through said second prong of said first clamp arm and locks said key of said first clamp arm in said second key groove. 